Gas burner apparatus for the generation of carbon monoxide and hydrogen



Dec. 6, 1955 P. GAUCHER 2,725,933

GAS BURNER APPARATUS F THE GENERATION OF CARBON MONOX ND HYDROGEN FiledM8. 195] L50 26/; c 5/? BY %iTToRA/EK5 2,725,933 Patented l)ec. 6, 1955I lice exas Company, New York, N. Y., a corporation of DelawareApplicationMa'y 3, 1951, Serial No. 224,275 3 Claims. (Cl. 158-99) Thisinvention relates to an apparatus and process for the partial combustionof gasiform hydrocarbons to produce carbon monoxide and hydrogen. Theinvention is particularly applicable to the partial combustion of agaseous hydrocarbon with enriched air or substantially pure oxygen'toproduce carbon monoxide and hydrogen. 0

In one'of its more specific aspects, this invention relates to apparatusparticularly suited for the partial combustron of fuel gas of highheating value, for example, natural gas, with substantially pure oxygen.

Gas mixtures consisting essentially of carbon monoxide 2 and hydrogenare commercially important as a source of hydrogen for hydrogenationreactions, as a source of feed gas for the synthesis of hydrocarbons,oxygenated organic compounds, ammonia, or the like. There is a greatdeal of interest at the present time in the production of carbonmonoxide and hydrogen by the partial combustion of a hydrocarbon with anoxygen-rich gas. Of especial interest is the reaction by which a gaseoushydrocarbon, such as methane or natural gas, is reacted withoxygen-enriched air or substantially pure oxygen.

The partial combustion of a hydrocarbon fuel with oxygen-enrichedair orwith relatively pure oxygen to produce carbon monoxide and hydrogenpresents unique problems not normally encountered in the burner art. Itis necessary to obtain very rapid and complete mixing of the reactants.This reaction also presents problems in protection of the burner, ormixer, from overheating. Because of the reactivity of oxygen with themetal itself from which a suitable burner may be fabricated, it isextremely important to prevent the burner elements from reaching thosetemperatures at which rapid oxidation of the elements takes place. Inthis connection, it is import'ant that the reaction between thehydrocarbon and oxygen take place entirely outside the burner proper andto prevent localized concentration of combustible mixarms at or near thesurface of the burner elements. The burner elements are subjected toheating by radiation from the reaction, even though the reaction takesplace beyond the point of discharge from the burner. Inadequate mixingresults in such concentrations of oxygen in localized areas thatrelatively complete combustion of a portion of the fuel takes place inthese areas. This releases large quantities of heat adjacent the burnerand overheats the burner elements by radiation. In addition, with anyoutlet configuration, there are formed eddy current mixtures of the twogases which will burn on the exposed metal surface (flame holders)unless these surfaces are cooled below the ignition temperature of thegas.

Another problem peculiar to this reaction is the tendency for freecarbon to form either on the burner or within the reaction space dueprimarily to inadequate mixing of the gases. The formation of carbon onthe surface of the burner often leads to burner failure, since itinterferes with the mixing of the gases and causes 10- calizedconcentrations of oxygen which overheat burner elements or associatedrefractory.

2 With conventional burners, it has been found: that it 1s necessary touses quantity of oxygen in excess of: the theoretical to prevent carbonformation. This aggravates the problem of cooling the burner an'd'oftencauses undesirable high reaction temperatures; Steam is sometimesrequired to control the reaction temperature and hold it at a reasonablelevel. The problem is further aggravated by the fact that in the partialcombustion: of gases, it is desirable to charge the reactant gases tothe burner in a highly preheated state to reducethe oxygen requirements"and give a maximum yield of the desired product gas. V

In the. generation of carbon monoxide and hydrogen from natural gas andrelatively pure oxygen for the synthesis of hydrocarbons in commercialquantities, it has been found that conventional burners areunsatisfactory for one or more reasons given above. These burnersgenerally are characterized by failure of burner elements, particularlyby burning away of metal at the burner tips even Where these elementshave been water cooled.

In the burner art, several'types of burners are known; In View of theforegoing discussion of problems, the type burner in which reactants arepremixed and injected from the burner at rates of flow in excess of therate of flame propagation suggests itself. This'type burner has'notproven satisfactory, however, with relatively pure oxygen andhydrocarbons, for example. The reason that these burners areunsatisfactory is that there is always present a film of gases along thesurface of the conduit or. orifice through which they are discharged andthis film is movingat a relatively slow rate. The'highly' reactiveoxygen-hydrocarbon mixture reacts along this filzmor surface sooncausing failure of the burner.

The present invention relates to burners in which the reactants aremixed at the point of discharge from'the burner, and in particular toburners of the annulus type, that is,- burners in which streams ofthe'reactant gases are introduced through concentric conduits, one ofthe gases being discharged from a central conduit into admixture with.the other of said gases which is discharged from the annular spacebetween the first conduit and a surrounding conduit. It is importantinthis type burner to insure rapid and adequate mixing of the reactantgases after they are discharged from the burner to prevent'localizedconcentrations of oxygen in the reaction'mixture which would result inhot spots near the burner.

It is also important to prevent the formation of mix tures of reactantsadjacent the burner elements, e. g., along the surface of an element.The elements must be adequately cooled, which is another importantproblem.

In the prior art burners of the type tov which this in vention relates,namely, annulus type burners, provision 5 is sometimes made for coolingthe tip of the burner by providing a cooling jacket through which watermay be supplied to cool the tip of the larger gas conduit.

An object of this invention is to provide a novel burner or mixer forthe partial combustion of fuel gases with gases rich in oxygen, forexample, enriched air or relatively pure oxygen, to produce carbonmonoxide and hydrogen. Another object of this invention is to provide anannulus type burner which is relatively simple in construction, whichinsures adequate mixing of the reactant gases, and which is provided innovel manner with protection against overheating and reaction of burnerelements with oxygen. A further object of this invention is to provide aburner assembly of the annulus type in which provision is made forcooling the discharge end of both the inner and outer conduit. Stillanother object is to provide a burnerassembly of the annulus type inwhich the discharge outlets are maintained in the same relativepositions regardless of expansion of the burner elements on heating.

Figure 1 is a sectional view of annulus type burner of this invention.Figure 2 is a sectional view of the burner of Figure 1 taken along line2-2 of Figure 1.

With reference to the drawings, the burner body comprises an innermember 3, approximately cylindrical in shape, and an outer member 4,also of generally cylindrical shape, is surrounding the inner member andspaced therefrom. The inner member is provided with a passageway 5extending along its axis for the passage of a stream of one of the gasestherethrough. A passage 6 for the second stream of gas is provided bythe annular spacing between the inner and outer members. The centralpassageway 5 terminates in an orifice 8, through which a stream ofreactant gas is discharged. A similar orifice 9 is provided at thedischarge end of passageway 6. Orifice 9 is symmetrical with orifice 8and slightly downstream from the point of discharge of orifice 8. One ofthe reactant gas streams is supplied to the passageway 5 through conduit11 from a supply line 12. The other reactant gas stream is introducedthrough conduit 13 into the annular passageway 6 from a supply line 14.Line 12 is disposed within line 14. Line 12 and manifold 14 may supplygases to a number of similar burners, each of which is connected to thesupply conduits 12 and 14 in the manner illustrated.

The inner body member 3 is spaced from the outer member 4 by a pluralityof webs 16 which serve to hold the elements rigidly in spacedrelationship with one another. Cooling of the discharge ports of theburner is accomplished by circulating cooling liquid through passagewaysor channels in the burner body. A stream of cooling liquid is introducedto the burner body through pipe 17 into a passageway 18 which extendsthrough the outer body member 4, through web 16; to a passageway 19 inthe inner member. Passageway 19 communicates with a cooling channel 21surrounding orifice 8. Channel 21 extends substantially completelyaround the orifice 8 and communicates with a passageway 22 through whichcooling liquid is discharged into a passageway 23 extending through web16' to passageway 24 in the outer body member. Passageway 24 conductsthe liquid to a cooling channel 26 disposed around orifice 9. Thechannel 26 extends substantially completely around the orifice 9 andterminates at passageway 27. Passageway 27 connects channel 26 withdischarge pipe 28. The cooling liquid discharged through pipe 28 may besupplied to a similar burner, not illustrated, and so on to cool anumber of burners in series. The relative order in which the orificesare cooled is unimportant, for example, the cooling liquid may be passedfirst through a channel disposed about the outer orifice and thenthrough the channel disposed about the inner orifice. It will also beobvious that means might be provided for supplying separate streams ofcooling liquid to each of the discharge orifices.

. invention,

An important feature of the burner of this invention is the provisionfor positively cooling the discharge ports of both the inner and outerconduit to protect the burner from overheating at these critical points.This is accomplished by passing the cooling liquid, suitably water, atrelatively high velocity through the channels in the burner bodyadjacent the discharge orifices or ports. The velocity of the liquidthrough the cooling channels should be at least feet per second foradequate cooling, and preferably greater than 30 feet per second. Thecooling channels are of relatively small cross-sectional area to insurerelatively high velocity flow through the channels. This prevents theformation of steam pockets in the cooling channel which would tend toblanket a section of the tip and permit overheating.

Another important feature of the burner of this invention is thesuspension of conduit 12 from the inner burner gas at body member 3 bymeans of conduit 11. The burner body may be supported on conduit 13which in turn is attached to supply manifold 14. Thus the inner conduit.12 is suspended in floating relationship within conduit 14 permittingrelative movement between the various conduits caused by thermalexpansion or contraction of the elements by heating or cooling. At thesame time body member 3 is positively positioned relative to outer bodymember 4 so that discharge ports 8 and 9 are maintained in fixed spacedrelationship to one another regardless of expansion or contraction ofthe elements on heating or cooling.

In operation, the burner is installed in the wall or fioor of a suitablefurnace. The refractory material forming the wall or floor surroundingthe burner is illustrated in the drawing and designated by numeral 29.

in a specific example, a plurality of burners 4 inches in outsidediameter are installed in an unpacked reactor. These burners arearranged in a compact cluster and supplied by common gas and oxygenmanifolds. The burners are cast of Inconel, an alloy steel containingabout 13 per cent chromium, 79.5 per cent nickel and 6.5 per cent iron.The inner feed pipe, corresponding to conduit 11 in the drawings, andthe inner header, corresponding to pipe 12 of the drawings, arefabricated of l38 steel, i. e., an alloy steel containing about 18 percent chromium and 8 per cent nickel. This material has a relatively highcoefiicient of expansion. The outer feed pipe and outer header,corresponding to conduits 13 and 14 of the drawing, are fabricated of achromium alloy steel containing 6 to 8 per cent chromium and having afairly low coefficient of expansion. Commercially pure oxygen, i. e.,oxygen of about 97 mol per cent purity, is fed at 260 F. through thecenter of the burner, while natural 980 F. is fed through the annulus.Cooling water is passed in series through a number of the burners. Thevelocity of flow in the cooling channels adjacent the orifices of eachburner is calculated as feet per second. The stream of gas dischargedfrom the annulus has a velocity approximately twice that of the centerorifice. The gas from the annulus is directed inward toward the streamfrom the center at an angle of about from the axis of the burner. Thegas velocity from the central orifice is about 100 feet per second.

The angle at which the stream from the annulus is discharged into thecentral stream may vary from about 30 to about from the axis of thecentral stream. The velocity of the streams may range from about 75 feetper second to about 300 feet per second. Preferably the velocity fromthe annulus is from 50 per cent to per cent in excess of the velocityfrom the central orifice.

Obviously, many modifications and variations of the as hereinbefore setforth, may be made without departing from the spirit and scope thereof,and therefore, only such limitations should be imposed as are indicatedin the appended claims.

I claim:

1. A burner structure for mixing a stream of gasiform hydrocarbon and astream of oxygen-containing gas which comprises a substantiallycylindrical inner body member having a central duct terminating in anoutlet for the passage of a stream of reactant therethrough, asubstantially cylindrical outer body member of larger diameter than saidinner body member and disposed about said inner body member to define anannular passageway thercbetween and terminating in an outlet adjacentand surrounding the outlet from said central duct for the passage of asecond stream of reactant therethrough, said inner body member having achannel adjacent and spaced about the outlet of said central duct forthe passage of cooling liquid therethrough, said outer body memberhaving channel adjacent and spaced about the outlet of said centralconduit for the passage of cooling liquid therethrough, a plurality ofwebs rigidly connecting said inner body member to said outer body memberat points spaced from the discharge ends of said body members, saidouter body member having a first passageway communicating with saidchannel thereof, said outer body member having a second passagewayextending from said channel thereof and through one of said webs to saidinner body member for establishing communication between the channels,said inner body member having a first passageway extending from saidsecond passageway in said outer body member to said channel of saidinner body member, said inner body member having a second passagewayextending through said one of said webs to said outer body member andcommunicating with the channel of said inner body member, said outerbody member having a passageway extending from said last mentionedsecond passageway, a first rigid conduit connected to said outer bodymember in supporting relationship therewith and communicating with saidannular passageway, a second rigid conduit rigidly connected to saidinner body member and communicating with said central duct, a first feedpipe rigidly connected to said first conduit at substantially a rightangle thereto, and a second feed pipe disposed within said first feedpipe and connected to said second conduit, said second conduitsupporting said second feed pipe within said first feed pipe in spacedrelationship with the walls of said first feed pipe.

2. Apparatus as defined in claim 1 wherein said outer conduit and saidouter feed pipe are fabricated of a material having a relatively lowco-ei'licient of thermal expansion and said inner conduit and said innerfeed pipe are fabricated of a material having a relatively high c0-eflicient of thermal expansion.

3. A burner structure which comprises a substantially cylindrical innerbody member having a central duct terminating in an outlet for thepassage therethrough of a stream of gas, a substantially cylindricalouter body member of larger diameter than said inner body member anddisposed about said inner body member to define an annular ducttherebetween terminating in an outlet adjacent and surrounding'theoutlet from said central duct, said inner body member having a channelof uniform restricted cross-sectional area substantially completelyencircling the outlet of said central duct for the passage of coolingliquid therethrough, said outer body member having a channel of uniformrestricted cross-sectional area substantially completely encircling theoutlet of said annular duct for the passage of cooling liquidtherethrough, a plurality of webs rigidly connecting said inner bodymember to said outer body member at points spaced from the dischargeends of said body members, the body members having passagewayscommunicating with said channels for supplying cooling liquid to saidchannels in series, a first rigid conduit connected to said inner bodymember and communicating with said central duct to supply a stream ofgas thereto, a second rigid conduit connected to said outer body memberin communication with said annular duct and disposed about said firstconduit, a feed pipe connected to said first conduit at substantially aright angle thereto to supply gas to said first conduit and a secondfeed pipe disposed about said first feed pipe and connected to saidsecond conduit to supply a second gas thereto.

References Cited in the file of this patent UNITED STATES PATENTS

3. A BURNER STRUCTURE WHICH COMPRISES A SUBSTANTIALLY CYLINDRICAL INNERBODY MEMBER HAVING A CENTRAL DUCT TERMINATING IN AN OUTLET FOR THEPASSAGE THERETHROUGH OF A STREAM OF GAS, A SUBSTANTIALLY CYLINDRICALOUTER BODY MEMBER OF LARGER DIAMETER THAN SAID INNER BODY MEMBER ANDDISPOSED ABOUT SAID INNER BODY MEMBER TO DEFINE AN ANNULAR DUCTTHEREBETWEEN TERMINATING IN AN OUTLET ADJACENT AND SURROUNDING THEOUTLET FROM SAID CENTRAL DUCT, SAID INNER BODY MEMBER HAVING A CHANNELOF UNIFORM RESTRICTED CROSS-SECTIONAL AREA SUBSTANTIALLY COMPLETELYENCIRCLING THE OUTLET OF SAID CENTRAL DUCT FOR THE PASSAGE OF COOLINGLIQUID THERETHROUGH, SAID OUTER BODY MEMBER HAVING A CHANNEL OF UNIFORMRESTRICTED CROSS-SECTIONAL AREA SUBSTANTIALLY COMPLETELY ENCIRCLING THEOUTLET OF SAID ANNULAR DUCT FOR THE PASSAGE OF COOLING LIQUIDTHERETHROUGH, A PLURALITY OF WEBS RIGIDLY CONNECTING SAID INNER BODYMEMBER TO SAID OUTER BODY MEMBER AT POINTS SPACED FROM THE DISCHARGEENDS OF SAID BODY MEMBERS, THE BODY MEMBERS HAVING PASSAGEWAYSCOMMUNICATING WITH SAID CHANNELS FOR SUPPLYING COOLING LIQUID TO SAIDCHANNELS IN SERIES, A FIRST RIGID CONDUIT CONNECTED TO SAID INNER BODYMEMBER AND COMMUNICATING WITH SAID CENTRAL DUCT TO SUPPLY A STREAM OFGAS THERETO , A SECOND RIGID CONDUIT CONNECTED TO SAID OUTER BODY MEMBERIN COMMUNICATION WITH SAID ANNULAR DUCT AND DISPOSED ABOUT SAID FIRSTCONDUIT, A FEED PIPE CONNECTED TO SAID FIRST CONDUIT AT SUBSTANTIALLY ARIGHT ANGLE THERETO TO SUPPLY GAS TO SAID FIRST CONDUIT AND A SECONDFEED PIPE DISPOSED ABOUT SAID FIRST FEED PIPE AND CONNECTED TO SAIDSECOND CONDUIT TO SUPPLY A SECOND GAS THERETO.